Known in the art is an apparatus for metering fluid comprising a measuring chamber having a free piston, the end spaces of the chamber being connected to a distributor of flows of the metered fluid, and a batch corrector having an abutment provided in the first end space of the measuring chamber and connected to a control unit. The batch is corrected by limiting stroke of an auxiliary plunger provided inside the free piston by moving said abutment (SU, A, 1219924). While this metering apparatus ensures a high enough metering accuracy, it is rather complicated in structure and is of a low reliability in operation.
Known in the art is an apparatus for metering fluid having a batch controller and a rotor accommodated in a fixed sleeve. The sleeve and the rotor have radial ports for the admission and discharge of metered fluid connected to respective pipelines. The inner passage of the rotor is closed of the ends thereof and is divided into measuring chambers by free pistons mounted therein. The measuring chambers are capable of regularly communicating with the radial ports and their number is equal to the number of discharge passages. One of the end sides of the inner passage of the rotor is closed by means of an abutment which is movable in the passage and is operatively connected to a mechanism for its movement to form a batch controller (cf. V. V. Bekman, Racing Cars. Leningrad. Mashinostroenie Publishing House. 1980. pp. 147-149). The latter is in the form of a sophisticated mechanical system consisting of a number of cooperating parts so as to lower reliability and response speed owing to inertia of the system.